There are many causes for allergies and sensitivities. Having a sluggish, plugged up liver that can't properly detox it's ongoing load of xenobiotic, etc, causes a toxic back up in your system which leads to allergies and sensitivities. The thymus gland can make false associations to energetic vibrational frequencies of manyy compounds. Leaky gut is one of the biggest contributing problems to allergies/sensitivities and is part of dysbiosis. Candida overgrowth is only one aspect of this picture and is not a factor in every case of dysbiosis. There can be many synergystic contributors to dysbiosis and thus leaky gut.